mirror of
https://github.com/LadybirdBrowser/ladybird
synced 2026-04-26 01:35:08 +02:00
3012c0fe72
Replace per-frame heap-allocated RefCounted ScrollFrame objects with a single contiguous Vector<ScrollFrame> inside ScrollState. All frames for a viewport are now stored in one allocation, using type-safe ScrollFrameIndex instead of RefPtr pointers. This reduces allocation churn, improves cache locality, and moves parent-chain traversal (cumulative offset, nearest scrolling ancestor) into ScrollState — similar to how visual context nodes were recently consolidated into AccumulatedVisualContextTree.
114 lines
3.3 KiB
C++
114 lines
3.3 KiB
C++
/*
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* Copyright (c) 2024-2025, Aliaksandr Kalenik <kalenik.aliaksandr@gmail.com>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#pragma once
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#include <LibGfx/Point.h>
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#include <LibWeb/Painting/ScrollFrame.h>
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namespace Web::Painting {
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class ScrollStateSnapshot {
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public:
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static ScrollStateSnapshot create(Vector<ScrollFrame> const& scroll_frames, double device_pixels_per_css_pixel);
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Gfx::FloatPoint device_offset_for_index(ScrollFrameIndex index) const
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{
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if (index.value() >= m_device_offsets.size())
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return {};
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return m_device_offsets[index.value()];
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}
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private:
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Vector<Gfx::FloatPoint> m_device_offsets;
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};
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class ScrollState {
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public:
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// ScrollFrameIndex is 1-based: value 0 means "no frame".
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// Index 0 in m_scroll_frames is a sentinel (never accessed by callers).
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// Value N maps directly to m_scroll_frames[N].
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ScrollState()
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{
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m_scroll_frames.empend(); // Sentinel at index 0
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}
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ScrollFrameIndex create_scroll_frame_for(PaintableBox const& paintable_box, ScrollFrameIndex parent)
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{
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auto index = ScrollFrameIndex { m_scroll_frames.size() };
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m_scroll_frames.empend(paintable_box, false, parent);
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return index;
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}
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ScrollFrameIndex create_sticky_frame_for(PaintableBox const& paintable_box, ScrollFrameIndex parent)
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{
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auto index = ScrollFrameIndex { m_scroll_frames.size() };
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m_scroll_frames.empend(paintable_box, true, parent);
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return index;
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}
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ScrollFrame const& frame_at(ScrollFrameIndex index) const { return m_scroll_frames[index.value()]; }
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ScrollFrame& frame_at(ScrollFrameIndex index) { return m_scroll_frames[index.value()]; }
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CSSPixelPoint cumulative_offset(ScrollFrameIndex index) const
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{
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CSSPixelPoint offset;
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while (index.value()) {
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offset += frame_at(index).own_offset();
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index = frame_at(index).parent_index();
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}
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return offset;
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}
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ScrollFrameIndex nearest_scrolling_ancestor(ScrollFrameIndex index) const
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{
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auto ancestor = frame_at(index).parent_index();
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while (ancestor.value()) {
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if (!frame_at(ancestor).is_sticky())
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return ancestor;
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ancestor = frame_at(ancestor).parent_index();
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}
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return {};
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}
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template<typename Callback>
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void for_each_scroll_frame(Callback callback)
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{
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for (size_t i = 1; i < m_scroll_frames.size(); ++i) {
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if (m_scroll_frames[i].is_sticky())
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continue;
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callback(ScrollFrameIndex { i }, m_scroll_frames[i]);
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}
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}
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template<typename Callback>
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void for_each_sticky_frame(Callback callback)
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{
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for (size_t i = 1; i < m_scroll_frames.size(); ++i) {
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if (!m_scroll_frames[i].is_sticky())
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continue;
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callback(ScrollFrameIndex { i }, m_scroll_frames[i]);
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}
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}
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void clear()
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{
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m_scroll_frames.resize_and_keep_capacity(1); // Keep sentinel at index 0
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}
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private:
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friend class ViewportPaintable;
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ScrollStateSnapshot snapshot(double device_pixels_per_css_pixel) const
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{
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return ScrollStateSnapshot::create(m_scroll_frames, device_pixels_per_css_pixel);
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}
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Vector<ScrollFrame> m_scroll_frames;
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};
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}
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